The amplifier is a Sony XM-2020, 20+20W RMS, I want to install only 2 speakers on the rear panel. In short, I'll have a cable starting from a little jack near the driver's seat, ending to the 2 rca connecting the amplifier (into the trunk). I'll connect my mp3 walkman to the jack plug, turning on the amplifier by a simple switch. My question is: what kind of speakers should I buy (brand/model/RMS power)? I don't want anything expensive, I was given the amplifier by a friend who changed his car. And what about Sony speakers (XS-F1037SE)? Are they suitable with that 20+20W amplifier?